Method of operating alternating-current motors.



PATENTED APR. 11 1905.

W. A. LAYMAN. METHOD OF OPERATING ALTERNATING CURRENT MOTORS.

APPLIOATION FILED SEPT 3. 1904.

nvvE/vrok 4 Waldo A. Layman.

UNITED STATES Patented April 11, 1905.

PATENT OFFICE.

WALDO A. LAYMAN, OF ST. LOUIS, MISSOURI.

SPECIFICATION forming part of Letters Patent No. 787,336, dated April11, 1905.

Original application filed December 28, 1903, Serial No. 186,848.Divided and this application filed September 3, 1904. Serial No.223,171.

To all whom it may concern:

Be it known that I, VVALDO A. LAYMAN, a citizen of the United States,residing at the city of St. Louis, State of Missouri. have invented acertain new and useful Method of Operating Alternating-Current Motors,of which the following is such a full, clear, and exact description aswill enable any one skilled in theart to which it appertains to make anduse the same, reference being had to the accompanying drawings, formingpart of this specification.

My invention relates to a method of operating alternating-currentelectric motors, and more particularly to the operation of that type ofsuch motors in which one of the members, preferably the rotor, isprovided with means, such as a commutator, for directing the currenttherein to produce definite magnetic poles at starting and also withmeans of any suitable character for short-circuiting the individualcoils of such member after starting.

1 do not claim herein the apparatus here shown and described, as such isthe subjectmatter of my original application, Serial No. 186,848, filedDecember 28, 1903, renewed August 25, 1904, No. 222,136, for electricmotor, of which the present application is a division relating moreparticularly to a method of operating such motors.

My invention therefore comprises, primarily, a method of operating analternating-current motor, which consists in directing the current inone of the members thereof to produce definite magnetic poles,short-circuiting said member,and subsequently increasing thenumber ofshort circuits in said member.

Referring now to the accompanying drawing, which illustratesdiagrammatically a motor adapted for practicing my method, 10 indicatesthe mains of the supply-circuit, furnishing single-phase alternatingelectric current to the field-coils 11, wound upon the cores 12.

13 is the armature-core, provided with the usual continuous winding 14,which is connected, by means of leads 15, with the segments of acommutator 16, upon which bear brushes 17, connected on locally closedcircuit by means of a conductor 18.

19 is a conductor-ring adapted to be clamped upon the segments of thecommutator 16 to short-circuit the same in the usual way.

20 indicates three slip-rings mounted to rotate with the armature of themotor and having three brushes 21 bearing upon them. These slip-rings 20are connected, by means of conductors 22, with three equidistant pointsof the armature-winding 14.

24 indicates short-circuiting conductors connected at one end to thebrushes 21 and at their other ends to the three divisions 25 of avariable resistance which is preferably ohmic in character.

26 is a switch-arm the extremities of which are adapted to move over andmake contact with the plates 27, connected to the resistance 25 togradually include said resistance in or exclude it from the armatureshort circuit.

In carrying out my method of operating such a motor the various parts ofthe device may at starting be in the positions shown in the accompanyingdrawing, and the resistance 25 may be of any desired value. Forinstance, it may be of such strength that at starting ninety per cent.of the current induced in the armature-winding will flow through theconductor 18, connecting the armature-brushes, and the remaining ten percent. of such current will flow through the resistance 25. When themotor has received its initial rotation under these conditions, theresistance 25 may be gradually excluded from the short circuit throughthe conductors 24 by suitably rotating the arm 26, and at the propermoment, preferably when normal run ning speed under load has beenattained and the resistance 25 is substantially excluded, theshort-circuiting ring 19 is clamped by suitable actuating means upon thecommutator 16 to short-circuit the segments thereof. It will thus beseen that in the practice of my method the greater part or, if desired,all of the armature-current flows at starting through the commutedcircuit and that the amount of such current passing through the shortcircuit 24,

containing the adjustable resistance, may be gradually increased, asdesired, by progressive exclusion of the resistance 25 until when normalrunning speed under load is approximated practically all of thearmature-current will pass through circuit 24, leaving the commutatorcircuit substantially inoperative. The number of short circuits in thearmature is then largely increased by moving the short-circuiting ring19 into contact with the commutator 16. The advantages of having a largenumber of individual short circuits in such an armature are wellrecognized, and it will be seen that by my method they are graduallyintroduced.

Having fully described my invention, what -I claim as new, and desire tosecure by Letters Patent of the United States, is

l. The method of operating alternating-current motors, which consists indirecting the current in one of the members thereof to produce definitemagnetic poles, short-circuiting said member, and increasing the numberof short circuits in said member.

2. The method of operating alternating-ain'- rent motors, which consistsin directing the current in one of the members thereof to producedefinite magnetic poles at starting, shortcircuiting said member, andincreasing the number of short circuits in said member after the motorhas started.

3. The method of operating alternating-current motors, which consists indirecting the current in one of the members thereof to produce definitemagnetic poles, gradually shortcircuiting said member, and increasingthe number of short circuits in said member.

4. The method of operating alternating-current motors, which consists indirecting a portion of the current in one of the members thereof toproduce definite magnetic poles, short-circuiting a portion of thecurrent in said member, and then increasing the number of short circuitsin said member.

5. The method of operating alternating-current motors, which consists indirecting a portion of the current in one of the members thereof toproduce definite magnetic poles, short-circuiting a portion of thecurrent in said member, varying the amount of the shortcircuitedcurrent, and increasing the number of short circuits in said member.

6. The method of operating alternating-current motors, which consists indirecting a portion of the current in one of the members thereof toproduce definite magnetic poles at starting, short-circuiting a portionof the current in said member before normal running speed is attained,varying the amount of the short-circuited current, and increasing thenumber of short circuits in said member when normal speed is attained.

In testimony whereof I have hereunto set my hand and affixed my seal inthe presence of the two subscribing witnesses.

WALDO A. LAYMAN. [L. s.]

lVitnesses:

l). C. BurJuiuAN, JAMES H. BRYSON.

